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The relationship between fidelity, amplitude damping coefficient, and unknown state coefficient.

Quantum secret-sharing scheme for noisy environments

To protect the confidentiality of a message during its transmission, people encrypt it. However, noise in the transmission channels can be a source of concern regarding how faithful the message transmission may be after it has been decrypted. This is particularly important for secrets shared using quantum scale messengers. For example, a classical secret takes the shape of a string of zeros and ones, whereas a quantum secret is akin to an unknown quantum state of two entangled particles carrying the secret. This is because no two quantum particles can be in the same state at any given time. In a new study published in EPJ D, Chen-Ming Bai from Shaanxi Normal University, Xi’an, China, and colleagues calculate the degree of fidelity of the quantum secret once transmitted and explore how to avoid eavesdropping.

The publishers of The European Physical Journal C – Particles and Fields are pleased to announce the appointment of Professor Kostas Skenderis as new Editor-in-Chief for Theoretical Physics II: Gravitation, Astroparticle Physics and Cosmology, General Aspects of Quantum Field Theories, and Alternatives, replacing Professor Ignatios Antoniadis.

Kostas Skenderis is Director of the Southampton Theory Astrophysics and Gravity (STAG) Research Centre and a Professor in Mathematical Sciences at the University of Southampton. His research interests are in high energy theoretical physics and string theory, and in particular in the study of holographic dualities, their foundations and their applications.

A new study investigates the extremely rapid changes in the density of electrons in specific sites of the caffeine molecules thanks to an ultra-fast laser pulse that persists long enough to be observed

Caffeine keeps physicists up at night. Particularly those concerned with the capacity of electrons to absorb energy. In a new study published in EPJ B, a Franco-Japanese team of physicists have used the caffeine molecule as a playground to test the effect of ionising radiation on its electrons as they approach excited states. Their model accounts for the ionisation phenomenon in electrons, which are in a site-specific, localised orbit in the caffeine molecule. The electron excitation leaves the door open to positive charge progression along a molecular backbone. Thomas Niehaus from Claude Bernard Lyon 1 University, France, and colleagues have now developed a method for quantifying this positive charge migration in line with the ultra-short laser impulse. The observed charge motion happens on an attosecond time scale charge rearrangements driven by nuclear motion.

Density of Bitcoin transaction where red crosses mark a specific community of owners.

New study of Bitcoin transactions reveals hidden owner communities and a high-concentration of wealth distributed between a few people

Cryptocurrencies like Bitcoin can be analysed because every transaction is traceable. This means that they are an attractive system for physicists to study. In a paper published in EPJ B, Leonardo Ermann from the National Commission for Atomic Energy in Buenos Aires, Argentina, and colleagues from the University of Toulouse, France, have examined the structure of the Bitcoin-owner community by looking at the transactions of this cryptocurrency between 2009 and 2013. The team’s findings reveal that Bitcoin owners are close to an oligarchy with hidden communities whose members are highly interconnected. This research has implications for our understanding of these emerging cryptocurrency communities in our society - as usual bank transactions are typically deeply hidden from the public eye. They could also be helpful to computer scientists, economists and politicians who could better understand handle them.

Mobile data can be (and has been) used to study a vast number of subjects related to human behavior. One of its potential applications is on epidemics, a complex field that is informed not only by healthcare, but also social interactions and human mobility. In this blog post, Stefania Rubrichi explains the context in which her team used a real mobile phone dataset in an attempt to better understand and tackle the spread of diseases. Their
study was just published in the journal EPJ Data Science.

New study of how positive and negative electrical charge disorder at the ends of polymers acts like a green or red light for proteins to pass through biological membranes

Nature’s way of allowing proteins across its gates, through porous biological membranes, depends, among others, on their electrical charge. For a protein to cross this type of membrane, it needs to be stimulated by an electrical field. A new study focuses on a particular kind of proteins that have multiple functions - dubbed Intrinsically Disordered Proteins - because the electric charge disorder on their surface makes it possible for them to take multiple shapes. In the work, recently published in EPJ E, Albert Johner from the Charles Sadron Institute (part of the CNRS) in Strasbourg, France and Jean-Francois Joanny from Paris reveal how the mixed electrical charge at the ends of the proteins influences biological membrane crossing. This has potential implications for our understanding of how proteins travel across the body, and of disease mechanisms.

Force microscopy image of the magnetisation structure for a part of the array of square elements.

Better understanding of the changing magnetic state of nanometric squares in an array could be the basis for future ultrahigh density data storage

The magnetisation of nanometric square material is not fixed. It moves around in a helical motion. This is caused by the electron whose degree of freedom, referred to as spin, which follows a precession motion centred on the middle of a square nano-magnet. To study the magnetisation of such material, physicists can rely on two-dimensional arrays of square nanomagnets. In a paper published in EPJ B, P. Kim from the Kirensky Institute of Physics, associated with the Russian Academy of Sciences, in Krasnoyarsk, Siberia, Russia, and colleagues have devised a new model taking into account the factors affecting the magnetic interaction between individual nanomagnets. Better controlling such nanomagnets arrays could have applications in ultrahigh density data storage,in an electronic application called spintronics exploiting electron spins and its magnetism, and in micro- and nanosurgery controlled by magnets.

New model examines the relative role of random interactions between individuals in a crowd compared to interactions stemming from their eagerness to be on their way

Ever found yourself crushed in a metro station at rush hour? The mathematician Carlo Bianca and physicist Caterina Mogno, both from the engineering research lab ECAM-EPMI in Cergy-Pontoise, France, have developed a new model to study the movement of crowds exiting a metro station. In a recent study published in EPJ Plus, they have for the first time employed models typically used to study gases consisting of a large number of molecules that collide at random (known as thermostatted kinetic theory) to study the consequences of the different interactions occurring among pedestrians in a crowd while exiting a metro station.

New study reveals theoretical calculation of new possible state for quantum particles which have received a photon

Quantum particles behave in mysterious ways. They are governed by laws of physics designed to reflect what is happening at smaller scales through quantum mechanics. Quantum state properties are generally very different to those of classical states. However, particles finding themselves in a coherent state are in a kind of quantum state which behaves like a classical state. Since their introduction by Erwin Schrödinger in 1926, coherent states of particles have found many applications in mathematical physics and quantum optics.

Now, for the first time, a team of mathematical physicists from Togo and Benin, call upon supersymmetry - a sub-discipline of quantum mechanics - to explain the behaviour of particles that have received a photon. These particles are subjected to particular potential energies known as shape-invariant potentials.

In a paper published in EPJ D, Komi Sodoga and colleagues affiliated with both the University of Lomé, Togo, and the University of Abomey-Calavi, in Cotonou, Benin, outline the details of their theory. These findings are relevant to scientists working on solving quantum optics and quantum mechanics applications.

The Soreq Applied Research Accelerator Facility (SARAF) is under construction in the Soreq Nuclear Research Center at Yavne, Israel. Phase I of SARAF (SARAF-I) is already in operation, generating scientific results in several fields of interest, especially the astrophysical s-process. When completed at the beginning of the next decade, SARAF-II will be a user facility for basic and applied nuclear physics, based on a 40 MeV, 5 mA CW proton/deuteron superconducting linear accelerator. This review presents first a technical overview of SARAF-I and II, including a description of the accelerator and its irradiation targets, and provides a survey of existing research programs at SARAF-I. It then describes in some detail the research potential at the completed facility. SARAF-II’s cutting-edge specifications, with its unique liquid lithium target technology, will enable world-competitive research plans in several disciplines: precision studies of beyond-Standard-Model effects by trapping light exotic radioisotopes (including meaningful studies already at SARAF-I); extended nuclear astrophysics research with higher-energy neutrons, including generation and studies of exotic neutron-rich isotopes relevant to the astrophysical r-process; nuclear structure of exotic isotopes; high-energy neutron cross sections for basic nuclear physics and material science research, including neutron-induced radiation damage; neutron-based imaging with an imaging plane flux similar to that of a 5 MW research reactor; accelerator-based neutron therapy; and, last but not least, novel radiopharmaceuticals development and production.